Our current society designates these constructions "wonders" since no society prior or following has replicated them. The greatest architectural feat of the Romans could arguably be their roads, spanning 400,000 kilometers (ten times the circumference of the Earth), but since roads have been prominent throughout history, the Roman system is less memorable in comparison. By the same logic, whatever future societies choose to idolize as "wonders" of the 21st century must be unique to the current era. Additionally, since historically the term "wonder" has been attributed exclusively to generally large architectural feats, and since we reside in a time and place where conservation of space is a pressing concern, the future will not be able to identify any "wonders of the world" as we know of them today.